Dynamic level control (DLC) is used in many systems to generate an audio signal with a desired loudness or amplitude based on an input signal with varying levels of amplitudes. DLC, also referred to as automatic gain control (AGC), has become important in network-based digital telephony systems, where a restricted gain or loss is introduced in a transmission path to maintain the transmitted signal level at a predetermined value. In this context, DLC is part of a broader class of voice quality enhancement (VQE) devices, which may include network echo cancellation, noise reduction, and other related signal enhancement processing elements.
In applications with small speakers, such as in phones, media players, mobile devices, and other components, DLC is used to boost and enhance the loudness and clarity of an audio signal. DLC may also be used to self-adjust the front-end gain of linear prediction analyzer-based phone codecs in such a way that the voice waveform is more accurately quantized by an analog-to-digital converter.
For radio, television, and home theater applications, DLC allows users to easily adjust the dynamic range of sound to avoid disturbing others, while still allowing users to hear a program without turning up the volume.